Deep-Ultraviolet Resonance Raman (DUVRR) Spectroscopy of Therapeutic Monoclonal Antibodies Subjected to Thermal Stress.

The structural assessment of Rituximab, an IgG1 mAb, was investigated with deep-ultraviolet resonance Raman (DUVRR) spectroscopy. DUVRR spectroscopy was used to monitor the changes to the secondary structure of Rituximab under thermal stress. DUVRR spectra showed obvious changes from 22 to 72 °C. Specifically, changes in the amide I vibrational mode were assigned to an increase in unordered structure (random coil). Structural changes in samples heated to 72 °C were related to loss in drug potency via a complement dependent cytotoxicity (CDC) bioassay. The DUVRR spectroscopic method shows promise as a tool for the quality assessment of mAb drug products and would represent an improvement over current methodology in terms of analysis time and sample preparation. To determine the scope of the method, protein pharmaceuticals of different molecular weights (ranging from 4 to 143 kDa) and secondary structure (β-sheet, α-helix and unordered structure) were analyzed. The model illustrated the method's sensitivity for the analysis of protein drug products of different secondary structure. Results show promise for DUVRR spectroscopy as a rapid screening tool of a variety of formulated protein pharmaceuticals.